Asphalt is an important large volume commodity which is generally derived from petroleum refinery streams such as vacuum residua.
Air-blowing is normally required to increase the viscosity and lower the penetration of the asphaltic material. During the air-blowing process, thermal and oxidative polymerization is effected, and the lower molecular weight resins are converted to asphaltenes.
Continuing research and development efforts have provided a variety of new and improved asphaltic compositions such as are described in U.S. Pat. Nos. 2,395,041; 2,701,213; 2,721,830; 2,767,102; 2,807,596; 2,848,429; 2,894,904; 2,909,441; 3,146,118; 3,264,206; 3,374,104; 3,462,359; 3,476,679; 3,563,778; 3,707,388; 3,725,240; 3,779,964; 3,790,519; 3,810,771; 3,869,417; 3,915,914; and the like.
Recent international economic developments have signaled the inevitable decline of petroleum as the world's supreme industrial commodity. The price of raw petroleum has increased several fold. Also, the consumption of petroleum has been increasing exponentially, and concomitantly the world petroleum supply has diminished to less than several decades of proven reserves.
The economics of upgrading petroleum refining residua into asphalt binders and other high value products is of increasing concern. Attention is being directed to coal-derived liquids as a potential abundant source of asphaltenes.
It was recognized by early workers that coal can be liquified by controlled heating in the substantial absence of oxygen. The conversion products are a liquid and a char. Because of the new compelling economic factors, the technology of coal liquefaction and gasification has been expanding at an accelerated pace. Pioneer developments in the field are represented by Lurgi and Fischer-Tropsch technology. More recent advances in coal liquefaction are described in U.S. Pat. Nos. 1,904,586; 1,955,041; 1,996,009; 2,091,354; 2,174,184; 2,714,086; 3,375,188; 3,379,638; 3,607,718; 3,640,816; 3,642,608; 3,705,092; 3,849,287; 3,870,621; inter alia.
One of the new developments in Fischer-Tropsch technology, i.e., the Sasol process, has been expanded into a commercial venture for converting low grade coal into synthesis gas, and a broad spectrum of organic derivatives such as fuel gas, light olefins, LPG, gasoline, light and heavy fuel oils, waxy oils, and oxygenated chemicals such as alcohols, ketones and acids. A byproduct of the Sasol commercial operation is coal tar.
The prospective advantages of combining coal-derived materials with petroleum-derived materials have not been readily achieved because of the general incompatibility of the two different categories of carbonaceous minerals.
Hence, there remains a pressing need for new technology to alleviate the dependence of industrial nations on petroleum as a critical raw material in energy and chemical applications, and a need for new technology to enhance the efficient conversion of petroleum refinery residua into valuable industrial products.
Accordingly, it is an object of the present invention to improve the economics of upgrading low value refractory petroleum residua into important industrial commodities.
It is another object of the present invention to provide a method for producing homogeneous blends of coal-derived and petroleum-derived materials.
It is another object of the present invention to provide a novel class of asphalt compositions produced from coal-derived carbonaceous material such as Sasol coal tar.
It is a further object of the present invention to improve the air-blowing qualities of marginal asphalt stock.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.